IPC::PubSub - Interprocess Publish/Subscribe channels

       Audrey Tang <cpan@audreyt.org>

       Copyright 2006, 2007 by Audrey Tang <cpan@audreyt.org>.

       This software is released under the MIT license cited below.

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perl v5.36.0                                       2022-11-27                                   IPC::PubSub(3pm)

       This module provides a simple API for publishing messages to channels and for subscribing to them.

       When a message is published on a channel, all subscribers currently in that channel will get it on their
       next "get" or "get_all" call.

       Currently, it offers four backends: "DBM_Deep" for on-disk storage, "Memcached" for possibly multi-host
       storage, "Jifty::DBI" for database-backed storage, and "PlainHash" for single-process storage.

       Please see the tests in t/ for this distribution, as well as "SYNOPSIS" above, for some usage examples;
       detailed documentation is not yet available.

       IPC::PubSub - Interprocess Publish/Subscribe channels

       IPC::DirQueue, where the subscribers divide the published messages among themselves, so different
       subscribers never see the same message.

           # A new message bus with the DBM::Deep backend
           # (Other possible backends include Memcached and PlainHash)
           my $bus = IPC::PubSub->new(DBM_Deep => '/tmp/pubsub.db');

           # A channel is any arbitrary string
           my $channel = '#perl6';

           # Register a new publisher (you can publish to multiple channels)
           my $pub = $bus->new_publisher("#perl6", "#moose");

           # Publish a message (may be a complex object) to those channels
           $pub->msg("This is a message");

           # Register a new subscriber (you can subscribe to multiple channels)
           my $sub = $bus->new_subscriber("#moose");

           # Publish an object to channels
           $pub->msg("This is another message");

           # Set all subsequent messages from this publisher to expire in 30 seconds
           $pub->expiry(30);
           $pub->msg("This message will go away in 30 seconds");

           # Simple get: Returns the messages sent since the previous get,
           # but only for the first channel.
           my @msgs = $sub->get;

           # Simple get, with an explicit channel key (must be among the ones
           # it initially subscribed to)
           my @moose_msgs = $sub->get("#moose");

           # Complex get: Returns a hash reference from channels to array
           # references of [timestamp, message].
           my $hash_ref = $sub->get_all;

           # Changing the list of channels we subscribe to
           $sub->subscribe('some-other-channel');
           $sub->unsubscribe('some-other-channel');

           # Changing the list of channels we publish to
           $pub->publish('some-other-channel');
           $pub->unpublish('some-other-channel');

           # Listing and checking if we are in a channel
           my @sub_channels = $sub->channels;
           my @pub_channels = $pub->channels;
           print "Sub is in #moose" if $sub->channels->{'#moose'};
           print "Pub is in #moose" if $pub->channels->{'#moose'};

           # Raw cache manipulation APIs (not advised; use ->modify instead)
           $bus->lock('channel');
           $bus->unlock('channel');
           my @timed_msgs = $bus->fetch('key1', 'key2', 'key3');
           $bus->store('key', 'value', time, 30);

           # Atomic updating of cache content; $_ is stored back on the
           # end of the callback.
           my $rv = $bus->modify('key' => sub { delete $_->{foo} });

           # Shorthand for $bus->modify('key' => sub { $_ = 'val' });
           $bus->modify('key' => 'val');

           # Shorthand for $bus->modify('key' => sub { $_ });
           $bus->modify('key');

           # Disconnect the backend connection explicitly
           $bus->disconnect;